1. Field of the Invention
This invention relates to cameras having protection covers to shutter the front of photographic objective lenses when not in use, and more particularly to cameras having protection covers with electric motors for charging the various protections of the camera whereby the opening and closing operation of said protection cover is performed by utilizing the driving force of the motor.
2. Description of the Prior Art
The conventional cameras have generally been provided with protection caps for the objective lenses in the releasably attached form to the camera housings in order to insure that when the camera is not in use, that is, when not in shooting, as the front or exposed-to-air lens surface of the photographic objective would otherwise attract dust, or be stained with dirt or fingerprints, the early grade of lens performance is still preserved, and that in such cases the photographic objective is protected from damages by direct contact with hard things. However, such protection caps have to be removed away from the camera housings when to shoot. Therefore, the photographers were hampered from the good management of their own cameras, and also liable to miss the isolated caps. In addition to such objections, there was a certain possibility of overlooking the removal of the protection cap from the front of the objective lens before a shot was made. Thus, the prior art protection means of such cap form gives to the cameras the drawbacks that the film is wastefully used up, or a good shutter chance is missed.
Attempts have been made in recent years to eliminate the above-described drawbacks by building the protection cover for the objective lens into the camera housing. The conventional arrangement of the protection cover has the following drawbacks:
That is, since the protection cover has despite the photographic objective even in the forwardly advanced position to move to the closing position in front of the photographic objective, the dimension of the conventional protection cover-built-in camera in the axial direction of the photographic objective becomes considerably larger than that of the protection cap-equipped camera. This is incompatible with the aim at an advance in the compactness of the camera. Further since the protection cover is arranged to be directly accessible by the operator, he must concentrate his deliberate effort on the control of the opening and closing operation of the protection cover, thus suffering the bad management.
It is also known to provide another type of protection cover-built-in camera in which when the protection cover is moving to the closing position, the objective lens is caused to move rearwards until the position for focusing on an infinitely distant object (focusing-at-infinity position) with an advantage that the axial dimension or width of the camera housing is minimized, as disclosed in U.S. Pat. No. 4,171,894 (filed Oct. 23, 1979). Since, however, this camera necessitates the direct handling of the protection cover by the operator and makes use of a drive connection between the mechanisms for closing the protection cover and for retracting the photographic objective, it follows that when to close the protection cover, the operator is obliged to apply to the protection cover the sum of a force necessary to move the protection cover to the closing position and a force necessary to move the photographic objective to the retracted position. For this reason, as a heavier stress than the normal level is felt, there is produced a problem that the manageability is deteriorated remarkably badly.
In short, the prior art protection cover-built-in cameras have either the drawback that the large increase in the width of the camera housing is unavoidable and the drawback that the quick and easy handling is very difficult in combination, or the drawback that the reduction of the width of the camera housing leads to further intensify the difficult handling, thus being a great annoyance to the ordinary photographers in practice.